EP0604721A2 - Magnetooptischer Fühler - Google Patents
Magnetooptischer Fühler Download PDFInfo
- Publication number
- EP0604721A2 EP0604721A2 EP93116552A EP93116552A EP0604721A2 EP 0604721 A2 EP0604721 A2 EP 0604721A2 EP 93116552 A EP93116552 A EP 93116552A EP 93116552 A EP93116552 A EP 93116552A EP 0604721 A2 EP0604721 A2 EP 0604721A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- magneto
- optic
- film
- integrated circuit
- laser beam
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 239000000523 sample Substances 0.000 title description 14
- 230000010287 polarization Effects 0.000 claims abstract description 31
- 238000000034 method Methods 0.000 claims abstract description 10
- 238000012360 testing method Methods 0.000 claims abstract description 10
- 230000005291 magnetic effect Effects 0.000 claims description 30
- NKBSIBTVPNHSIK-UHFFFAOYSA-N 2,3-dichloro-6,7-dimethylquinoxaline Chemical compound ClC1=C(Cl)N=C2C=C(C)C(C)=CC2=N1 NKBSIBTVPNHSIK-UHFFFAOYSA-N 0.000 claims description 10
- 230000005294 ferromagnetic effect Effects 0.000 claims description 9
- 239000013307 optical fiber Substances 0.000 claims description 9
- 239000002223 garnet Substances 0.000 claims description 8
- 239000000758 substrate Substances 0.000 claims description 8
- 239000011575 calcium Substances 0.000 claims description 6
- 239000000835 fiber Substances 0.000 claims description 5
- ZPDRQAVGXHVGTB-UHFFFAOYSA-N gallium;gadolinium(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Ga+3].[Gd+3] ZPDRQAVGXHVGTB-UHFFFAOYSA-N 0.000 claims description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 2
- 229910052791 calcium Inorganic materials 0.000 claims description 2
- 238000001816 cooling Methods 0.000 claims description 2
- 230000001939 inductive effect Effects 0.000 claims description 2
- 230000005298 paramagnetic effect Effects 0.000 claims description 2
- 239000000382 optic material Substances 0.000 description 64
- 239000010408 film Substances 0.000 description 16
- 239000000463 material Substances 0.000 description 16
- 239000004020 conductor Substances 0.000 description 15
- 230000008859 change Effects 0.000 description 14
- 230000000694 effects Effects 0.000 description 9
- 230000003287 optical effect Effects 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 230000005374 Kerr effect Effects 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 230000035945 sensitivity Effects 0.000 description 5
- 230000001360 synchronised effect Effects 0.000 description 5
- -1 europium chalcogenides Chemical class 0.000 description 3
- 239000003302 ferromagnetic material Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- 229910052693 Europium Inorganic materials 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 238000003384 imaging method Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- RWPPFCLXSXWWDM-UHFFFAOYSA-N [As].[Mn].[In] Chemical compound [As].[Mn].[In] RWPPFCLXSXWWDM-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 229910001940 europium oxide Inorganic materials 0.000 description 1
- AEBZCFFCDTZXHP-UHFFFAOYSA-N europium(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Eu+3].[Eu+3] AEBZCFFCDTZXHP-UHFFFAOYSA-N 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 239000005355 lead glass Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- GCSIELJPGDPWNK-UHFFFAOYSA-N selanylideneeuropium Chemical compound [Eu]=[Se] GCSIELJPGDPWNK-UHFFFAOYSA-N 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000002887 superconductor Substances 0.000 description 1
- OSSGWZIRURPXNK-UHFFFAOYSA-N tellanylideneeuropium Chemical compound [Eu]=[Te] OSSGWZIRURPXNK-UHFFFAOYSA-N 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/74—Record carriers characterised by the form, e.g. sheet shaped to wrap around a drum
- G11B5/82—Disk carriers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/02—General constructional details
- G01R1/06—Measuring leads; Measuring probes
- G01R1/067—Measuring probes
- G01R1/07—Non contact-making probes
- G01R1/071—Non contact-making probes containing electro-optic elements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/28—Testing of electronic circuits, e.g. by signal tracer
- G01R31/302—Contactless testing
- G01R31/308—Contactless testing using non-ionising electromagnetic radiation, e.g. optical radiation
- G01R31/311—Contactless testing using non-ionising electromagnetic radiation, e.g. optical radiation of integrated circuits
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/127—Structure or manufacture of heads, e.g. inductive
- G11B5/33—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only
- G11B5/39—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects
- G11B5/3903—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects using magnetic thin film layers or their effects, the films being part of integrated structures
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
- G11B5/855—Coating only part of a support with a magnetic layer
Definitions
- This invention relates to magneto-optic probes and, more particularly, to measuring the magneto-optic polarization rotation in a thin film magnetic film for imaging the spatial and temporal current distribution in an adjacent material such as an integrated circuit.
- a magnetic field passing through certain materials such as a magneto-optic material will change its index of refraction in the direction of the magnetic field which is known as the Faraday effect.
- a polarized light beam passing through a magneto-optic material will be subject to the change of the index of refraction resulting in an apparent rotation of the polarized light.
- the amount of rotation is an indication of the change of the index of refraction, which in turn is an indication of the instantaneous amplitude of the magnetic field.
- U.S. Patent 4,956,607 which issued on September 11, 1990 to M. Abe et al. shows an arrangement including a polarizer, a magneto-optic element, an analyzer and a light sensitive element for measuring the polarization rotation of the light for measuring the current in a power line by directing a beam of light through the polarizer and magneto-optic element in the direction of the magnetic field.
- the magneto-optical element may include yttrium-iron-garnet (YIG) material or ferromagnetic glass and lead glass.
- U.S. Patent 4,947,107 which issued on August 7, 1990 to R.W. Doerfler et al. describes a sensor for sensing the magnitude of current flowing in a conductor based upon the Faraday effect.
- a polarized light beam passes through a magneto-optic element without substantial internal reflection in the magneto-optic element wherein the element rotates the plane of polarization of the input beam in proportion to a magnetic field coupled in parallel to the light beam.
- U.S. Patent 4,933,629 which issued on June 12, 1990 to Y. Kozuka et al. describes a method and apparatus for measuring the strength of an AC electric field based on a light beam which is transmitted through and thus modulated by an optical sensing head due to the Pockel's and Faraday effects while the sensing head is exposed to the AC electric and magnetic fields.
- a polarized light beam passes through an optical element and then an analyzer and light sensitive element.
- U.S. Patent 4,823,083 which issued on April 18, 1989 to P.L. Meunier describes a head for measuring of magnetic fields using the effect of the magnetic field on polarization of light.
- a light beam is directed through a ferromagnetic material such as yttrium-iron-garnet (YIG) wherein the light beam experiences a rotation of its planar polarization owing to the Faraday effect caused by the magnetic field.
- YIG yttrium-iron-garnet
- U.S. Patent 3,418,036 which issued on December 24, 1968 to F. Holtzberg et al.
- europium chalcogenides in pure form or in solid solutions with other rare earth chalcogenides have far larger V constants than other materials commonly known in the art.
- Europium chalcogenides may include, for example, europium sulfide, europium selenide, europium oxide and europium telluride.
- a method and apparatus for measuring the current distribution in an integrated circuit or other material with high time resolution comprising the steps of positioning a magneto-optic material such as a ferromagnetic film in proximity to the surface of an integrated circuit or other material whereby the ferromagnetic film is in a magnetic field formed by currents in the integrated circuit, launching electrical pulses in the integrated circuit, reflecting a laser beam from the lower surface of a ferromagnetic film, and measuring the magneto-optic polarization rotation induced in the reflected laser beam by the ferromagnetic film.
- a magneto-optic material such as a ferromagnetic film
- the invention further provides synchronizing the reflection of the laser beam with the launching of electrical pulses which may be repeated a number of times to provide an output signal of the current at an instant of time whereby the current can be imaged with 1 psec time resolution.
- YIG yttrium-iron-garnet
- Y 3-x Ca x Fe 2( Fe 3-x Si x )O where x is ⁇ 2.
- Fig. 1 shows a block diagram of a magneto-optic prober 10 for measuring the current distribution in an integrated circuit with high time resolution.
- Pulse generator 12 generates a trigger pulse over lead 13 to an input of laser source 14.
- Laser source 14 may be, for example, a diode laser, a titanium sapphire laser which may, for example, operate at 2 watts output, and a dye laser which may be, for example, 100 mW and have a wavelength in the range from 560 to 670 nanometers. Other monochromatic light sources would be suitable for a laser source 14.
- An optical beam is coupled from laser source 14 as shown by arrow 15 to linear translator 16.
- Linear translator 16 functions to provide a time delay in the range from 0 to 10 nanoseconds to the optical path length of the light beam from laser source 14.
- Time delay controller 17 functions to control the optical path length by way of mechanical linkage 18 to linear translator 16.
- the optical beam from linear translator 16 shown by arrow 19 is coupled through collimator 20 to linear polarizer 21.
- Collimator 20 functions to collimate the input light beam shown by arrow 19 to provide a collimated output beam shown by arrow 22.
- Linear polarizer 21 functions to polarize the input light beam shown by arrow 22 to provide a linearly polarized light beam over fiber optic cable 23 to lens 24.
- Optical fiber 23 may be a single mode optical fiber for conveying the linearly polarized light beam from linear polarizer 21 shown by arrow 25.
- Lens 24 functions to provide an output light beam shown by arrow 26 over path 27 to magneto-optic material 28.
- Magneto-optic material 28 may be positioned over integrated circuit 29 so as to place magneto-optic material 28 in magnetic fields of the conductors of integrated circuit 29. Magneto-optic material 28 may also be cooled to a predetermined temperature such as below room temperature or below 78°centigrade, the temperature of liquid nitrogen. Refrigerator 30 functions to provide a coolant path over duct 31 to chamber 32. Integrated circuit 29, as well as magneto-optic material 28 may be located in chamber 32. A temperature sensor 33 may be positioned in chamber 32 having an output coupled over lead 34 to an input of thermostat 35. Thermostat 35 functions to control the temperature of chamber 32 and has an output coupled over lead 36 to refrigerator 30 to cool magneto-optic material 28 and chamber 32.
- Test circuitry 40 functions to respond to the trigger pulse on lead 13 to provide waveforms over, for example, leads 41 and 42 to integrated circuit 29 for testing the circuitry of integrated circuit 29.
- the waveforms on leads 41 and 42 may cause current to flow in certain conductors in integrated circuit 29.
- test circuitry 40 when a trigger pulse is generated on lead 13, test circuitry 40 generates waveforms causing internal waveforms and internal currents in integrated circuit 29 which are repeatable after an adequate time period to allow transients to settle.
- Lead 13 is also coupled to an input of time delay controller 17 so that, for example, time delay controller 17 may provide increments of delay after a number of trigger pulses have occurred on lead 13.
- time delay controller 17 may scan a current waveform in an integrated circuit 29.
- Lead 13 is also coupled to storage device 46.
- An electrical output of time delay controller 17 indicative of the delay is coupled over lead 47 to an input of storage device 46.
- Storage device 46 functions to store the polarization rotation signal appearing on lead 48 along with the time delay on lead 47 with the trigger pulse on lead 13.
- Storage device 46 may have an output coupled over lead 49 to display 50.
- Display 50 functions to display the polarization rotation signal as a function of time.
- the polarization rotation signal is generated by the light beam shown by arrow 54 along path 55 after passing through magneto-optic material 28.
- the light beam shown by arrow 54 passes into beam splitter 56 which may be, for example, a Thompson beam splitter to provide two light beams shown by arrows 57 and 58 which are directed to respective photodiodes 59 and 60.
- Photodiodes 59 and 60 function to detect the amount of polarized light received from beam splitter 56.
- the output of photodiode 59 is coupled over lead 61 to an input of sample and hold circuit 62.
- Sample and hold circuit 62 functions to hold the output signal of photodiode 59 and to provide an output over lead 63 to an input of differential amplifier 64.
- Photodiode 60 is coupled over lead 65 to an input of sample and hold circuit 66.
- the output of sample and hold circuit 66 is coupled over lead 67 to an input of differential amplifier 64.
- Differential amplifier functions to provide an output signal on lead 48 at times there is a change in the amplitude of the respective inputs on lead 63 and 67.
- Beamsplitter 56 and photodiodes 59 and 60, in conjunction with differential amplifier 64, provides a means for measuring the magneto-optic polarization rotation induced in the light beam passing through the magneto-optic material which may be, for example, a ferromagnetic film.
- Figure 2 is a perspective view of the magneto-optic material 28 in relation to integrated circuit 29.
- a light beam shown by arrow 26 follows path 27 to magneto-optic material 28.
- the light beam enters magneto-optic material 28 and is reflected at the bottom surface and passes back through magneto-optic material 28 and out shown by arrow 54.
- the change in the polarization rotation due to a change in the index of refraction due to the local magnetic field is known as the Faraday effect. If the light beam shown by arrow 26 is reflected by the upper surface of magneto-optic material 28 then the change in polarization rotation due to the local magnetic field is known as the Kerr effect.
- Either the Faraday effect or the Kerr effect may be used in interrogating magneto-optic material 28 with a polarized light beam.
- the light beam shown by arrow 26 may be directed to the magneto-optic material 28 where it passes over a conductor 70 of integrated circuit 29 to detect the currents in conductor 70.
- Magneto-optic material 28 may be a film on a substrate wherein the film is placed adjacent to conductor 70. Alternately, magneto-optic material 28 may be conformally formed over integrated circuit 29. An insulation layer, if necessary, may be inserted between magneto-optic material 28 and integrated circuit 29 to prevent shorting if the magneto-optic material is of low ohmic resistance. A conformal coating of magneto-optic material on integrated circuit 29 would provide maximum spatial resolution and sensitivity to the currents in conductor 70.
- Figure 3 is a cross-section view of an integrated circuit and magneto-optic material thereover.
- magneto-optic material 28 may be formed on a substrate 80 which is transparent to the light beams shown by arrows 26 and 54.
- Light beam 26 passes through substrate 80 and through magneto-optic material 28 to the lower surface 81 of magneto-optic material 28.
- Lower surface 81 may have a reflecting coating 82.
- Reflecting coating 82 may be, for example, aluminum having a thickness of, for example, 30 nm which is sufficient to reflect the polarized light beam without being conductive and shorting out conductor 70 to other conductors on integrated circuit 29.
- Substrate 80 may have on its upper surface 84 a quarter wave anitreflection coating to prevent the polarized light beam from being reflected from surface 84.
- the spacing between magneto-optic material 28 and the upper surface 86 of integrated circuit 29 may be in the range from 1 to 10 micrometers as shown by arrow 87.
- the thickness of magneto-optic material 28 may be in the range from 1 to 10 micrometers as shown by arrow 88. In the case where magneto-optic material is conformally coated on upper surface 86, the thickness of the magneto-optical material may be adjusted to be a quarter wavelength of the light being used to pass through the magneto-optic material.
- test circuitry 40 shown in Fig. 1 may include a coil or coils for inducing Eddy currents in the sample to be investigated or to subject the sample to a magnetic field which may be time varying or constant. Further, test circuitry 40 may include electrodes for placing an electric field across the sample which may be time varying or constant.
- Magneto-optic material 28 may be, for example, europium sulfide which is cooled to or below the temperature of liquid nitrogen, i.e. 78°C..
- Magneto-optic material 28 may be calcium-doped yttrium-iron-garnet which may be represented by the formula Y 3-x Ca x Fe 2( Fe 3-x Si x ) O where x ⁇ 2.
- Calcium doped yttrium-iron-garnet (YIG) orders ferromagnetically just below room temperature.
- Gadolinium-gallium-garnet (GGG) is ferromagnetic at room temperature. More sensitivity can be obtained with magneto-optic materials having a higher magnetic susceptibility at room temperature.
- the light beam shown by arrow 26 may be a pulse in the range from .5 to 10 psec and may be focussed to a narrow spot depending on the wavelength of the light beam which may be in the visible or infrared range.
- a spot size impinging on and passing through magneto-optic material 28 on lower surface 81 may be as small as 1 micrometer in diameter.
- the index of refraction of the magneto-optic material 28 changes by virtue of the magnetic field in the material locally and causes a change in the linear polarization of the light beam.
- the change in polarization of the light beam due to the change in the index of refraction causes the light beam shown by arrow 54 to have a rotation in polarization.
- the component of light travelling through the magneto-optic material in the direction of the magnetic field is affected by the change in index of refraction in that direction.
- the apparent rotation of the linear polarization of the light beam may be in the range from 0 to 5° rotation and have a sensitivity such as 4x106 degrees rotation per cmT.
- the rotation of the linear polarization of the light beam may be used to determine the amplitude or the magnitude of the instantaneous local magnetic field that the light beam passed through, which in turn, is a measure of the current in conductor 70 where conductor 70 is the only conductor in close range to cause the magnetic field in magneto-optic material 28 above conductor 70.
- a laboratory test was made using the embodiment shown in Fig. 1 without chamber 32, refrigerator 30, sensor 33, and thermostat 35.
- the light pulse was 1 psec long.
- the magneto-optic material was GGG which is non-conducting with a reflecting layer of 300 ⁇ of aluminum similar to the embodiment shown in Fig. 3 except that anti-reflection coating 85 was absent.
- the arrangement of integrated circuit and magneto-optic material 28 is shown in Fig. 2 and Fig. 3.
- the thickness of the magneto-optic material was 10 micrometers.
- Fig. 4 is a graph of the polarization rotation signal versus time with respect to the trigger pulse on lead 13.
- Linear translator 16 moved the 1 psec pulse from -20 to 90 ps shown in Fig. 4.
- the ordinate represents polarization rotation signal in arbitrary units and the abscissa represents time with respect to the trigger pulse.
- Test circuitry 40 provided a square wave pulse to conductor 70 having a duration of about 80 psec.
- Curve 92 in Fig. 4 shows the output signal on lead 48 shown in Fig. 1 over the range from -20 to 90 ps time where the sampling pulse of 1 psec duration is scanned from -20 to 90 psec.
- the temperature of the magneto-optic material was 300° Celsius during the time data was taken for curve 92.
- Laser source 14 was a dye laser tuned to a wavelength in the range from 560 to 670 nm.
- the polarization rotation signal shown in Fig. 4 did not exceed 5°.
- Fig. 5 shows an alternate embodiment of the invention.
- like references are used for functions corresponding to the apparatus of Figs. 1 - 3.
- Optical fiber 23 is cleaved at end 95 and a layer of magneto-optic material 96 is formed thereon.
- the magneto-optic material 96 may be the same as the materials used for magneto-optic material 28.
- the fiber may be hand held or mechanically held and conveniently moved or mechanically positioned over and against the surface or close to the surface of integrated circuit 29 shown in Fig. 1.
- the light beam shown by arrow 26 and a reflected light beam shown by arrow 54 would stay in optical fiber 23 until it was coupled in or out at end 97.
- End 97 of optical fiber 23 would optically be coupled to a source of linear polarized light and to a beam splitter for detecting the polarization rotation in the reflected polarized light after passing through magneto-optic material 96 and back.
- Laser source 14 and beam splitter 56 shown in Fig. 1 would be suitable.
- a reflecting layer 82 may be formed over magneto-optic material 96.
- Figure 6 shows an apparatus for obtaining stroboscopic images of the instantaneous current distribution in integrated circuit 29.
- a sensitive polarizing microscope 100 is used to receive a reflected light beam along path 55 shown by arrow 54.
- Polarizing microscope functions to record the magneto-optic rotation pattern induced in magneto-optic material 28.
- the time-delayed probe laser beam is directed along path 27 shown by arrow 26 and illuminates the entire magneto-optic material 28 or a portion thereof. Coupling to the magneto-optic material 28 will, in general, alter the performance to some degree: for cases in which this problem is significant, the image must be acquired by scanning a small area.
- the magneto-optic material 28 may be operated to exhibit the Farday effect or the Kerr effect.
- Figure 7 is a cross-section view of an integrated circuit 29 and magneto-optic material 28.
- Light beam 106 is shown impinging on surface 107 of magneto-optic material 28.
- Surface 107 reflects light beam 106 as light beam 108.
- Light beam 108 will experience a polarization rotation due to the Kerr effect dependent upon the magnetic field in magneto-optic material 28.
- An example of a material useful for the embodiment shown in Fig. 7 is indium manganese arsenic (InMnAs).
- InMnAs indium manganese arsenic
- the invention describes an apparatus and method for measuring the current distribution in an integrated circuit with 1 psec time resolution by measuring the magneto-optic polarization rotation induced in a thin paramagnetic or ferromagnetic film.
- a thin film of europium sulfide grown atop a transparent substrate is placed film side down on the integrated circuit and cooled below 78° Celsius.
- Electrical pulses in the circuit are launched synchronous with probe laser pulses, using a photo-sensitive or electrical trigger.
- the probe pulses are time-delayed relative to the electrical pulses using a mechanical delay line, such as a linear translator allowing imaging of the current distribution at an arbitrary instant of time during the course of the pulse propagation.
- Spatial resolution of 1 - 2 micrometers can be obtained by focussing the probe beam with a small lens onto a slide coated with a uniform film of magneto-optic material or by scanning a single-mode optical fiber with europium sulfide or other suitable material deposited on a cleaved end.
- the current sensitivity of the detector scales with the thickness of the magneto-optic film.
- the film thickness is limited to the order of 100 nm by the strong optical absorption, yielding a current density of 10 mA/ ⁇ Hz. If infrared light is used, the film thickness may be increased to 1 micrometer without degrading the spatial resolution, for a concomitant sensitivity of the order of 1 mA/ ⁇ Hz.
- europium sulfide is selected for the ferromagnetic material, cooling to at least liquid nitrogen temperature is required.
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Health & Medical Sciences (AREA)
- Computer Vision & Pattern Recognition (AREA)
- Electromagnetism (AREA)
- Toxicology (AREA)
- General Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Manufacturing & Machinery (AREA)
- Tests Of Electronic Circuits (AREA)
- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
- Testing Or Measuring Of Semiconductors Or The Like (AREA)
- Measuring Magnetic Variables (AREA)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US968719 | 1992-10-30 | ||
US07/968,719 US5451863A (en) | 1992-10-30 | 1992-10-30 | Fiber optic probe with a magneto-optic film on an end surface for detecting a current in an integrated circuit |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0604721A2 true EP0604721A2 (de) | 1994-07-06 |
EP0604721A3 EP0604721A3 (de) | 1995-03-29 |
Family
ID=25514666
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP93116552A Withdrawn EP0604721A3 (de) | 1992-10-30 | 1993-10-13 | Magnetooptischer Fühler. |
Country Status (3)
Country | Link |
---|---|
US (2) | US5451863A (de) |
EP (1) | EP0604721A3 (de) |
JP (1) | JPH06213976A (de) |
Families Citing this family (33)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5612131A (en) * | 1993-04-26 | 1997-03-18 | International Business Machines Corporation | Composite magneto-optic memory and media |
US6084396A (en) * | 1994-03-31 | 2000-07-04 | Intel Corporation | Method for performing quantitative measurement of DC and AC current flow in integrated circuit interconnects by the measurement of magnetic fields with a magneto optic laser probe |
US6169408B1 (en) * | 1996-09-30 | 2001-01-02 | Motorola, Inc. | Method and apparatus for testing an integrated circuit with a pulsed radiation beam |
US6571183B1 (en) | 1998-10-05 | 2003-05-27 | University Of Maryland | Imaging using spatial frequency filtering and masking |
US6608494B1 (en) * | 1998-12-04 | 2003-08-19 | Advanced Micro Devices, Inc. | Single point high resolution time resolved photoemission microscopy system and method |
US6657446B1 (en) * | 1999-09-30 | 2003-12-02 | Advanced Micro Devices, Inc. | Picosecond imaging circuit analysis probe and system |
US6483327B1 (en) * | 1999-09-30 | 2002-11-19 | Advanced Micro Devices, Inc. | Quadrant avalanche photodiode time-resolved detection |
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Also Published As
Publication number | Publication date |
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JPH06213976A (ja) | 1994-08-05 |
EP0604721A3 (de) | 1995-03-29 |
US5451863A (en) | 1995-09-19 |
US5663652A (en) | 1997-09-02 |
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